Gun recoil damping structure



HP0/m47 SAMJz//ey Ww@ F eb. 24, 1942.

G. M. MAGRUM ETAL GUN RECOIL DAMPING STRUCTURE Filed April 22, 193sPatented Feb. 24, 1942 UNITED STATES PATENT OFFICE GUN RECOIL DAMPINGSTRUCTURE Gervase M. Magrnm and Frank M. Salisbury,

Buffalo, N. Y.; said Magrum assignor to Houde. Engineering Corporation,Buffalo, N. Y., a corporation of New York, and said Salisbury assignorto Bell Aircraft Corporation, Buffalo, N. Y., a corporation of New YorkApplication April 22, 1938, Serial No. `203,500

3 Claims.

This invention relates to the dampening or the absorption of the shockof recoil in guns, particularly guns of the machine or rapid fire type,such as guns mounted on airplanes.

In guns of the type referred to, the barrel structure is 'axiallymovable relative to the gun mounting, and the gunner grips the mountingadjacent to the breech endof the barrel structure for directioning andaiming of the barrel structure and for manipulation of the triggermechanismfor firing of the gun. When the gun is red, the barrelstructure recoils and moves back toward the operator, and unless suchrecoil movement is dampened or` absorbed, directioning, aiming andfiring of the gun will be materially interferred with, withcorresponding loss in accuracy as well as unnecessary discomture to thegunner and unnecessary strain on the gun.

An important object of our invention is to provide simple and efficientstructure on the gun for dampening and absorbing the recoil shock, saidstructure being preferably of the hyjdraulictype.

A further object is to provide shock absorbing structure which can bereadily applied to a gun without material increase of the gun size orbulk and which will not interfere with the balanced and eflicientmanipulation and firing of the gun. The abovev and other features of ourinvention are incorporated in the structure disclosed on theaccompanying drawing, in which drawing:

Figure 1 is a plan view, more or less diagrammatic, of a gun structureshowing our improved shock absorbing means applied thereto;

Figure 2 is an enlarged section on plane II-II of Figure 1; and

Figure 3 is an enlarged section of the hydraulic fluid flow controllingvalve structure.

Referring to Figure 1, the gun structure support may be in the form of`apost or pedestal I0 having at its lower end a pin II for journaling inthe socket of a suitable base (not shown) which may be stationarilymounted, as on an airplane or which base may have a tripod or othersupport so that the gun structure may be portable. The post or pedestalI0 may be U- shaped and between its side walls I2 and I3 the gun barrelbody i4 is received and guided, the zgn barrel I5 extending forwardlyfrom said At the breech end of the gun barrel structure is a cross-frameI6 supporting grips I1 and I'I and the trigger mechanism I8 between thegrips. A projection from the breech end of the gun barrel structureextends through a cap I9 secured tothe frame I6.

At its end the frame I6 has socket extensions 2D and 20 for receivingthe inner ends of tubes 2| and 2l respectively, these tubes extendingforwardly parallel with the gun barrel structure. Secured on the tubes2l and 2|' are brackets 23 and 23 receiving trunnion pins 24 and 24supported by and extending laterally from the walls I2 and I3 of thepedestal I0. The frame IB and the tubing extending therefrom thus form aframework which may be swung in a vertical plane on the trunnion pivotand which can be swung in a lateral direction with the post I0 on theaxis of the pivot pin II.

In accordance with our invention we provide shock absorbing structures Sand S' whose stationary or cylinder elements C are the outer ends oftubes 2l and 2| respectively and Whose piston elements P are connectedto the forward end of the barrel structure body I4 so that thisstructure is vertically supported at its forward end, the barrelstructure being thus axially shiftable under recoil but under control ofthe shock absorber structure.

The-details of construction of the shock absorber mechanism is shown inFigures 2 and 3. The outer ends of the tubes 2| and 2 I are reamed toform the cylinder element C, and a plug 25 secured by a rivet 28 formsthe inner cylinder head. In order to seal this end of the cylinder, asoft gasket 21 is tightly squeezed against the head by a washer 28 heldby a screw 29.

Secured to the .outer end of cylinder tube, as by welding, is 'a flange30 to which is detachably secured, as by screws 3l, the outer head orbody 32, the head end 32' extending a distance into the cylinder tube,the head 32 being thus rigidly secured to the cylinder tube co-axialtherewith.

The head 32 has the inner bore 33 communicating with the space withinthe cylinder tube 2|, and an outer bore 3) lof less diameter. The pistonrod 35 extends through these bores and in the bore 34 is a bearingbushing 36 of suitable metal for the rod. The outer end of the body 32is expanded to form a recess for suitable packing assembly 31 around thepiston rod to prevent leakage. vSecured to the outer end of the rod 35is an eye 38, the gun barrel body structure I4 having laterallyextending lugs 39 and 39 to which the outer ends of thel piston rods ofthe shock absorber structures are connected as by screws extendingthrough the apertures of the eyes 38.

At its inner end, each piston rod has a reduced piston 42. The piston islscrewed tightly against f theshoulder 43 and the piston rod and islocked Ythe piston rod 35 has the bore 48 extending through the neck 4|for communication with the space within the valve housing chamber. Atits outer end, the bore 48 is connected by passages 63S with thecylinder space at the outer side of the, piston. The connection of thebore 48 with the cylinder'space at the inner side of the piston iscontrolled by a valve 50 which, as shown, is a thin metal disc having ametering orifice a spring 52 within the valve housing tending to holdthe valve disc seated against the inner end of the piston rod across theend of the bore 48.

Seating against the shoulder between the bores 33 and 34 of the head 32is a washer 53 and on the piston rod is an annular flange or collar 54.A spring 55 within the cylinder wall 2l abuts the washer 28 and the base44 of the valve housing, the spring being centered by the valve housingand by a boss'or lug 5B on the washer 28. The

spring forms part of the shock absorber action and tends to resistinward movement of the piston 'structure and to hold the pistonstructure in outerposition with the flange or collar 54 in abutment withthe washer 53.

Each shock absorber body structure 32 has a top extension 51 providing afilling and expansion chamber for hydraulic iiuid, the chamber beingclosed by a cover 59.` A ller screw 6D allows filling of the shockabsorber working.

Aportion or neck 4| threaded for reception of a back into firingposition, and during outward movement of the piston structure thesuction created in tle inner or high pressure working chambers willunseat the valve discs for comparatively free flow from the low pressureworking chambers to the high pressure working chambers. The increasinglength of piston rod entering the low pressure chamber will create avolume differential between the working chamber but the excess uid mayflow into the chambers 58 to be returned to the working chambers duringoutward stroke of the piston structures so that both low and highpressure working chambers will be refilled with hydraulic fluid.

The valve discs may be very thin so that the orices 5| would be of thesharp edge type so as to compensatejor change in the viscosity of thehydraulic fluid' and the hydraulic shock absorber resistance will remainuniform independently of viscosity variation, By providing shockabsorbers at opposite sides of the gun barrelr structure and paralleltherewith, the shock ab-V l inspection, adjustment or repair, and withthe piston forms the high pressure working chamber.

When the gun is red, it recoils, or in other words moves back toward theoperator and, un-

less the recoil were checked or dampened, accurate firing would beprevented. However, when the shock absorber structure is applied to thegun and the gun barrel structure recoils, the

shock absorber piston structure will be shifted inwardly in the cylinderstructure, and the spring will'be compressedand will resist and cushionsuch'inward movement. At the same time, the uid in the inner or highpressure working chamber of each shockVv absorber is displaced by thepiston andthe pressure against the valve disc r5|) will keep the discseated so that the displaced iiuid can escape only through therestricted ori- IVfice 5| for' ow through' the piston bore 48 andpassages 49 to the outer or low pressure working chamber 33, theresistance to iiow through shock absorbers applied as shown they willadd very little to the bulk of the gun and will not interfere with theproper directioning, aiming, firing or other manipulations of the gun.

We have shown a practical and efllcient embodiment and application ofour invention but we do not desire to be limited to the exactconstruction, arrangement and operation shown and described as changesand modifications may be made without departing from the scope of theinvention.

We claim as follows:

l. A gun structure comprising a barrel body having a gun barrelextending from the forward end thereof, means to support said body fortilting, said means comprising a U-shaped support, a frame comprising apair of elongated tubes disposed extending one along each side of saidbody, respectively, and connected adjacent the breech end of said bodyby' a crossmember connected with the breech end of said body, said tubesbeing each pivotally connected to a free armof said U-shaped support andadjacent the forward end of said tubes, means connecting said frame withthe forward end of said barrel body for controlled longitudinal movementof said body with respect to saidframe', said means comprising pistonsentered)A slidable in the forward end of said tubes, respectively,piston rods connected to said pistons and Apivotally connected at theirforward ends to the forward end of said body, each of said tubes beingprovided with a kplug abutment member therein and secured thereto, andbeing provided with compression spring means disposed extending betweensaid pistons and said plugs, housings defining an oil reservoir and alsodefining guides for said piston rods, said housings each compris'- ing atubular body having a reduced portion entered in the forward end ofatube and having an enlarged portion in abutting relation to the forwardend of a tube, and means on said housing forming a sealed connectionwith a piston rod slidable therein. y

2. In a gun structure which includes a -frame comprising a'pair ofvspaced elongated tubes and a gun barrel body disposed between saidtubes, means connecting said frame and said barrel body for support ofsaid bodyand for controlled relative movement of said body and frame,said means including a pair of tubular housings, one

, for each of said elongated tubes, with each oi' said housings having aportion thereof entered in the forward end of a tube, a rst flange onthe forward end of each tube, respectively, a second ange on each ofsaid housings, respectively, and removably secured to a first ange, eachof said housings being providedwith a piston rod slidable therein andextending therethrough, with each piston rod being pivctally connectedat one end to the forward end of said barrel body and having a piston onits other end entered in said tube, and means in each of said tubes andin each of said housings arranged cooperable with said pistonsto/,control relative movement of said barrel body and said frame.

3. In a gun structure which includes a. frame comprising a pair ofspaced elongated tubes and a gun barrel body disposed between saidtubes,

means connecting said frame and said barrel body for support of saidbody and for controlled relative movement of said body and said frame,said means comprising a pair of tubular housings, one for each of saidelongated tubes, with each of said housings having a portion thereofentered in the forward end of a tube, a first flange on the forward endof each tube, respectively, a second flange on each of said housings,respectively, and removably secured to a rst ilange, each of saidhousings being provided with a piston rod slidable therein and extendingtherethrough, with each piston rod being' pivotally connected at one endto the forward end of said barrel body and having a piston on its otherend entered in a said elongated tube, each of said housings beingprovided with a bored side boss arranged providing an oil reservoir influid communication with a said elongated tube to which the housing isconnected, each of said piston rods carrying a valve housing entered ina said tube, and a valve in each of said valve housings, respectively.

' GERVASE M. MAGRUM. FRANK M. SALISBURY.

